Windshield wipers for modem automotive vehicles typically have several operating modes, such as fast, normal, and intermittent, that may be selected manually with a switch, dial, or sliding control. A driver generally activates the wiper system when the view through the windshield becomes distorted or obscured because of accumulated precipitation. The intermittent operating mode allows the driver to select a frequency of wiper operation that matches the intensity or rate of precipitation. When operated at the optimum speed and/or frequency, a windshield wiper provides good driver visibility without the distraction and annoyance of excessive activation.
When driving in conditions of variable precipitation, drivers often find themselves continually adjusting the speed and/or frequency of windshield wiper operation. Because each setting of the conventional wiper control provides a fixed speed and rate of activation, the setting must be manually adjusted every time the rate of precipitation changes. This increases driver workload (and annoyance) and diverts the driver's attention away from the task of driving the vehicle. What is needed, therefore, is a device for automatically controlling a windshield wiper to provide the optimum speed and/or frequency of operation in response to changing rates of precipitation. Such a device would provide an improvement in safety as well as driver convenience.